运行环境TC2.0.一个立方体内，有两条线段，求线段在xoy，yoz，xoz面上的投影，若两条投影不垂直，通过旋转显示让其垂直。-Runtime environment TC2.0. A cube, there are two lines, line segments in xoy, yoz, xoz plane projection, if two vertical projection does not, by rotating display to the vertical.